Abstract
This work presented a novel core-shell MnO2@m-SiO2 for catalyzing the removal of dyes from wastewater. MnO2 nanorods were sequentially coated with polydopamine (PDA) and polyethyleneimine (PEI) forming MnO2@PDA-PEI. By taking advantage of the positively charged amine groups, MnO2@PDA-PEI was further silicificated, forming MnO2@PDA-PEI-SiO2. After calcination, the composite MnO2@m-SiO2 was finally obtained. MnO2 nanorod is the core and mesoporous SiO2 (m-SiO2) is the shell. MnO2@m-SiO2 has been used to degrade a model dye Rhodamine B (RhB). The shell m-SiO2 functioned to adsorb/enrich and transfer RhB, and the core MnO2 nanorods oxidized RhB. Thus, MnO2@m-SiO2 combines multiple functions together. Experimental results demonstrated that MnO2@m-SiO2 exhibited a much higher efficiency for degradation of RhB than MnO2. The RhB decoloration and degradation efficiencies were 98.7% and 84.9%, respectively. Consecutive use of MnO2@m-SiO2 has demonstrated that MnO2@m-SiO2 can be used to catalyze multiple cycles of RhB degradation. After six cycles of reuse of MnO2@m-SiO2, the RhB decoloration and degradation efficiencies were 98.2% and 71.1%, respectively.
Highlights
IntroductionDyes are widely used in the textiles, cosmetics, paper, leather, ceramics, and inks industries [1,2]
Dyes are widely used in the textiles, cosmetics, paper, leather, ceramics, and inks industries [1,2].It is estimated that 15% of the dye is lost during processes and is released in wastewater [2].Dye pollutants are an important source of environmental contamination and cause significant pollution to groundwater [3]
Consecutive use of MnO2 @mesoporous SiO2 (m-SiO2) has demonstrated that MnO2 @m-SiO2 can be used to catalyze multiple cycles of rhodamine B (RhB) degradation
Summary
Dyes are widely used in the textiles, cosmetics, paper, leather, ceramics, and inks industries [1,2]. Dyes are generally resistant to light and moderate oxidative agents. Various materials have been used as adsorbents for the removal of dyes, such as biocoagulants [1], fruit peels [3], and cellulose-based bioadsorbents [4]. Silica-based materials, carboxylic acid-functionalized silica [15,16], silica-alumina oxide [17], silica hydrogels [18], mesoporous silica [19,20], and carboxymethyl tamarind-g-poly(acrylamide)/silica [21] have been investigated as adsorbents for removing dyes from wastewater. Except for the physical adsorption methods, removing dyes can be accomplished through oxidation, such as electrooxidation [22], photocatalytic degradation [23], and oxidation by graphene oxide nanosheet-based material [24].
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